Method of manufacturing illumination device, illumination device, illumination device manufacturing system, method of classifying color tone of light emitting devices, and method of classifying light emitting devices

ABSTRACT

In a method of manufacturing an illumination device, a color tone of each of a plurality of light emitting devices having different color tones is detected. In which region among a first region, a second region, a third region, a fourth region, a fifth region, and a sixth region on a chromaticity diagram the color tone of each of the plurality of light emitting devices is is determined based on the detected color tone. The chromaticity diagram has a first color tone area and a second color tone area in which the first color tone area is provided. The second color tone area is divided into the first region through the sixth region. The plurality of light emitting devices are classified into the first region through the sixth region based on the determined color tone.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35U. S. C. §119 toJapanese Patent Application No. 2014-052846, filed Mar. 15, 2014 andJapanese Patent Application No. 2015-041827, filed Mar. 3, 2015 Thecontents of these applications are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing anillumination device, an illumination device, an illumination devicemanufacturing system, a method of classifying color tone of lightemitting devices, and a method of classifying light emitting devices.

2. Description of the Related Art

In recent years, light emitting chips (semiconductor light emittingelements) as well as light emitting devices, which combine a lightemitting element with phosphor material that absorbs light from thelight emitting element and re-emits light at a different wavelength fromthe light emitting element, have been used in various types ofillumination (lighting) devices. However, even when the light emittingdevices are manufactured in the same manner, semiconductor chip andphosphor variation results in light emitting devices with differentcolor temperature, chromaticity, and light intensity characteristics.For this reason, the light emitting devices are ranked and sorted(binned or graded) according to their light emission characteristics.

When multiple light emitting devices are used to manufactureillumination apparatus, it is desirable for all illumination apparatusto have uniform characteristics such as color temperature, chromaticity,and light flux. For example, lighting apparatus chromaticity rangestandards (refer to FIGS. 8 and 9) are specified by JIS (JapaneseIndustrial Standard) and ANSI (American National Standards Institute),and white-light obtained from an illumination apparatus may be requiredto be within a standard specified chromaticity range, or depending onthe application, may be required to be within an even narrowerchromaticity range. In particular, it is desirable for the lighttemperature to also be within a JIS specified light temperature alongthe black-body (radiator) locus (or Planck curve in color space).

However, standard light emitting device grade selection might beinsufficient for producing illumination apparatus with this kind ofminimal variation (dispersion) in illumination characteristics, andfurther (tighter) binning to obtain desired chromaticity or light fluxresults in increased manufacturing cost.

On the other hand, by combining light from light emitting devices thatemit different colors, and specifically where those colors have acomplementary relation, it is possible to produce light that appears (tothe naked eye) as the targeted color. Consequently, various lightemitting device mounting schemes have been proposed to produce anillumination device that emits light within a desired color range byassembling a plurality of component devices that individually emitdifferent colors even outside the desired color range.

For example, with the purpose of making a pleasing white-lightillumination apparatus for lighting applications, light emitting devicesare used that have chromaticity located (in color space) outside thearea of a 3-step MacAdam ellipse around a targeted color temperature,which lies on the black-body locus and is considered suitable forwhite-light illumination. A light emitting apparatus has been proposed(Japanese Laid-Open Patent Publication 2013-45544) that is characterizedby a light emitting device module carrying a plurality of light emittingdevices, which emit light that merges to emit with approximately thesame chromaticity as the targeted chromaticity even though each of theplurality of light emitting devices has chromaticity lying outside the3-step MacAdam ellipse at the targeted chromaticity.

In the manufacture of apparatus for light emitting device applicationsother than lighting, such as liquid crystal display backlighting, lightemitting devices having the desired color temperature as well as lightemitting devices having other color temperatures are used to produce anoverall uniform color temperature. Manufacture results in differentgrades (color ranking) of the component light emitting devices and theirmaximum utilization is an (additional) issue. Accordingly, a method ofmanufacturing light emitting device application apparatus (JapaneseLaid-Open Patent Publication 2008-147563) has been proposed with thefollowing steps. A color temperature distribution data acquisition stepgathers color temperature distribution data that include colortemperature coordinates for light emitting devices manufactured at eachdesignated production facility. An optimum color temperature groupingstep identifies groups of light emitting devices, which emit mergedlight with a specified color temperature based on the acquired colortemperature distribution data, and forms those groups in a manner thatmaximizes light emitting device utilization. An optimum colortemperature sorting and mounting step sorts and mounts subgroups oflight emitting devices identified as optimal for the light emittingdevice application apparatus such that the merged light of the subgroupshas the prescribed color temperature.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, in a method ofmanufacturing an illumination device, a color tone of each of aplurality of light emitting devices having different color tones isdetected. In which region among a first region, a second region, a thirdregion, a fourth region, a fifth region, and a sixth region on achromaticity diagram the color tone of each of the plurality of lightemitting devices is is determined based on the detected color tone. Thechromaticity diagram has a first color tone area and a second color tonearea in which the first color tone area is provided. The second colortone area is divided into the first region through the sixth region. Theplurality of light emitting devices are classified into the first regionthrough the sixth region based on the determined color tone.

According to another aspect of the present invention, an illuminationdevice is manufactured by a method. In the method, a color tone of eachof a plurality of light emitting devices having different color tones isdetected. In which region among a first region, a second region, a thirdregion, a fourth region, a fifth region, and a sixth region on achromaticity diagram the color tone of each of the plurality of lightemitting devices is is determined based on the detected color tone. Thechromaticity diagram has a first color tone area and a second color tonearea in which the first color tone area is provided. The second colortone area is divided into the first region through the sixth region. Theplurality of light emitting devices are classified into the first regionthrough the sixth region based on the determined color tone.

According to further aspect of the present invention, an illuminationdevice manufacturing system includes memory, a first color tone bin, afirst bin, a second bin, a third bin, a fourth bin, a fifth bin, a sixthbin, a color tone detector, a classifying device, and a mounting device.The memory is to store a reference chromaticity data including a rangeof chromaticity for color tone classifying which includes a first colortone area and a second color tone area in which the first color tonearea is provided. The second color tone area is divided into a firstregion, a second region, a third region, a fourth region, a fifthregion, and a sixth region. The first region and the second region areprovided opposite to each other to sandwich the first color tone areabetween the first region and the second region. The third region and thefourth region are provided opposite to each other to sandwich the firstcolor tone area between the third region and the fourth region. Thefifth region and the sixth region are provided opposite to each other tosandwich the first color tone area between the fifth region and thesixth region. The first color tone bin, the first bin, the second bin,the third bin, the fourth bin, the fifth bin, and the sixth bin areprovided to respectively correspond to the first color tone area and thefirst region through the sixth region. The color tone detector isconfigured to detect a color tone of each of a plurality of differentcolor tone light emitting devices. The classifying device is configuredto determine which of the first color tone area and the first regionthrough the sixth region each of the plurality of different color tonelight emitting devices belongs to based on the color tone detected bythe color tone detector with reference to the reference chromaticitydata stored in the memory so as to dispatch each of the plurality ofdifferent color tone light emitting devices into one of the first colortone bin and the first bin through the sixth bin. The mounting device isconfigured to extract from the plurality of different color tone lightemitting devices dispatched in the first color tone bin and the firstbin through the sixth bin first light emitting devices in the first binand second light emitting devices in the second bin, and configured tomount the first light emitting devices and the second light emittingdevices on a circuit board with disposition to merge and mix lightoutput from the first light emitting devices and the second lightemitting devices.

According to the other aspect of the present invention, in a method ofclassifying color tone of light emitting devices, each of a plurality oflight emitting devices having different color tones is classified into afirst region, a second region, a third region, a fourth region, a fifthregion, and a sixth region in a color tone area including a first colortone area and a second color tone area in which the first color tonearea is provided. The second color tone area is divided into the firstregion, the second region, the third region, the fourth region, thefifth region, and the sixth region. Outlines of the first region throughthe sixth region are defined by first three points of intersection on aperimeter of the second color tone area at which a trianglecircumscribed outside the first color tone area intersects with theperimeter of the second color tone area and second three points ofintersection on the perimeter of the second color tone area at whichdividing lines that pass through the first three points of intersectionand a center of the second color tone area intersect with the perimeterof the second color tone area.

According to the other aspect of the present invention, in a method ofclassifying light emitting devices, a color tone of each of a pluralityof light emitting devices having different color tones is detected. Inwhich region among a first region, a second region, a third region, afourth region, a fifth region, and a sixth region on a chromaticitydiagram the color tone of each of the plurality of light emittingdevices is is determined based on the detected color tone. Thechromaticity diagram has a first color tone area and a second color tonearea in which the first color tone area is provided. The second colortone area is divided into the first region through the sixth region. Theplurality of light emitting devices are classified into the first regionthrough the sixth region based on the determined color tone.

According to the other aspect of the present invention, in a method ofmanufacturing an illumination device, the illumination device ismanufactured using a plurality of light emitting devices classified by amethod. In the method, each of the plurality of light emitting deviceshaving different color tones is classified into a first region, a secondregion, a third region, a fourth region, a fifth region and a sixthregion in a color tone area including a first color tone area and asecond color tone area in which the first color tone area is provided.The second color tone area is divided into the first region, the secondregion, the third region, the fourth region, the fifth region and thesixth region. Outlines of the first region through the sixth region aredefined by first three points of intersection on a perimeter of thesecond color tone area at which a triangle circumscribed outside thefirst color tone area intersects with the perimeter of the second colortone area and second three points of intersection on the perimeter ofthe second color tone area at which dividing lines that pass through thefirst three points of intersection and a center of the second color tonearea intersect with the perimeter of the second color tone area.

According to the other aspect of the present invention, an illuminationdevice is manufactured by a method. In the method, the illuminationdevice is manufactured using a plurality of light emitting devicesclassified by a method. In the method, each of the plurality of lightemitting devices having different color tones is classified into a firstregion, a second region, a third region, a fourth region, a fifth regionand a sixth region in a color tone area including a first color tonearea and a second color tone area in which the first color tone area isprovided. The second color tone area is divided into the first region,the second region, the third region, the fourth region, the fifth regionand the sixth region. Outlines of the first region through the sixthregion are defined by first three points of intersection on a perimeterof the second color tone area at which a triangle circumscribed outsidethe first color tone area intersects with the perimeter of the secondcolor tone area and second three points of intersection on the perimeterof the second color tone area at which dividing lines that pass throughthe first three points of intersection and a center of the second colortone area intersect with the perimeter of the second color tone area.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is an abbreviated diagram illustrating a method of binning lightemitting devices for the first embodiment of the present invention;

FIG. 2 is a graph showing the distribution of light emitting devicechromaticity on a chromaticity diagram;

FIG. 3 is an abbreviated diagram illustrating a method of binning lightemitting devices for the second embodiment of the present invention;

FIG. 4 is a schematic cross-section drawing showing a light emittingdevice for an embodiment of the present invention;

FIG. 5 is a schematic drawing showing an illumination device for anembodiment of the present invention;

FIG. 6 is an abbreviated diagram illustrating a method of binning lightemitting devices for the fourth embodiment of the present invention;

FIG. 7 is an abbreviated diagram illustrating a method of binning lightemitting devices for the third embodiment of the present invention;

FIG. 8 is a diagram showing ANSI chromaticity regions and 7-step MacAdamellipses on a CIE 1931 (x, y) chromaticity diagram;

FIG. 9 is a diagram showing ANSI chromaticity regions and 7-step MacAdamellipses on a CIE 1976 (u′, v′) chromaticity diagram;

FIG. 10 is a graph showing 3-step MacAdam ellipse and 5-step MacAdamellipse areas plotted on a CIE 1931 (x, y) standard chromaticitydiagram;

FIG. 11 is the graph of FIG. 10 showing an example where the mergedlight has chromaticity not within the 3-step MacAdam ellipse; and

FIG. 12 is a block diagram illustrating the illumination devicemanufacturing system.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

The following describes embodiments of the method of binning(classifying) light emitting devices, method of manufacturing anillumination device, illumination device, and illumination devicemanufacturing system of the present disclosure with reference to thefigures.

For illustrative purposes, the drawings may have color sorting regionsor light emitting device constituent elements exaggerated in part or inentirety. In addition, for clarity, even when a figure illustrates across-section, the cross-section region may not be designated withoblique cross-hatching.

An embodiment of a method of manufacturing an illumination device mayinclude: determining a color tone of a plurality of light emittingdevices having different color tones; and binning the light emittingdevices into a first color tone area, a first region, a second region, athird region, a fourth region, a fifth region, and a sixth regiondepending on the determined color tone of each of the light emittingdevice, the first color tone area being set on a chromaticity diagramand a second color tone area that is outside the first color tone areabeing set on the chromaticity diagram in which the second color tonearea being further divided into the first region through sixth region.

According to another embodiment of a method of manufacturing anillumination device, the first region through sixth region may bedivided into pairs: the first region and the second region, the thirdregion and the fourth region, and the fifth region and the sixth region,such that each region is positioned opposite its paired region on theother side of the first color tone area.

According to another embodiment of a method of manufacturing anillumination device, it may further includes mounting at least one firstlight emitting device which is binned in the first region, and at leastone second light emitting device which is binned in the second region,with disposition that merges and mixes light output from each of thelight emitting devices.

According to another embodiment of a method of manufacturing anillumination device, it may further includes mounting at least one thirdlight emitting device which is binned in the third region, and at leastone fourth light emitting device which is binned in the fourth region,with disposition that merges and mixes light output from each of thelight emitting devices.

According to another embodiment of a method of manufacturing anillumination device, it may further includes mounting at least one fifthlight emitting device which is binned in the fifth region, and at leastone sixth light emitting device which is binned in the sixth region,with disposition that merges and mixes light output from each of thelight emitting devices.

According to another embodiment of a method of manufacturing anillumination device, the first region through sixth region are regionsdefined by: vertices A, B, C of a triangle that inscribes the firstcolor tone area and is inscribed inside the second color tone area,which is concentric with the first color tone area, and dividing linesAD, BE, CF that pass through the center O of the second color tone areaand divide the second color tone area into six regions.

According to another embodiment of a method of manufacturing anillumination device, the first region through sixth region are regionsdefined by: vertices A, B, C of a triangle that is inscribed inside thesecond color tone area and has sides that intersect with the perimeterof the first color tone area at three or more points, and dividing linesAD, BE, CF that pass through the center O of the second color tone areaand divide the second color tone area into six regions.

According to another embodiment of a method of manufacturing anillumination device, two of the dividing lines extend in the longdirection of the second color tone area.

According to another embodiment of a method of manufacturing anillumination device, the first color tone area and the second color tonearea have elliptical shapes.

According to another embodiment of a method of manufacturing anillumination device, the first color tone area is a 3-step MacAdamellipse.

According to another embodiment of a method of manufacturing anillumination device, the chromaticity diagram is a CIE x, y chromaticitydiagram or a CIE LUV chromaticity diagram.

According to another embodiment of a method of manufacturing anillumination device, light output from each of the light emittingdevices is merged and mixed to output white-light, and the center of thefirst color tone area is positioned on or along the black-body locus, ortowards the x-axis from the black-body locus.

According to another embodiment of a method of manufacturing anillumination device, reference chromaticity data for sorting is storedin memory, the reference chromaticity data being the range set on achromaticity diagram as the first color tone area and the second colortone area, which is outside the first color tone area, the second colortone area being divided into the first region, second region, thirdregion, fourth region, fifth region, and sixth region, and the firstregion and second region, the third region and fourth region, and thefifth region and sixth region being paired off to sandwich the firstcolor tone area between the two regions of each pair, binning the lightemitting devices into a first color tone area, a first region, a secondregion, a third region, a fourth region, a fifth region, and a sixthregion depending on the determined color tone of each of the lightemitting device, the first color tone area being set on a chromaticitydiagram and a second color tone area that is outside the first colortone area being set on the chromaticity diagram in which the secondcolor tone area being further divided into the first region throughsixth region, in binning the light emitting devices, the referencechromaticity data sorted in memory is referred to determine each lightemitting device belongs to which of the first color tone region, andfirst through sixth regions based on the color tone determined, andbased on those determinations, dispatch each light emitting device intoone of a first color tone bin, first bin, second bin, third bin, fourthbin, fifth bin and sixth bin, each of which corresponds to the firstcolor tone area, first through the sixth regions and the first lightemitting devices from the first bin and second light emitting devicesfrom the second bin are extracted and mounted on a circuit board withdisposition that results in merging and color-mixing the light outputfrom each light emitting device.

According to another embodiment of a method of manufacturing anillumination device, in determining which region each light emittingdevice belongs to, if the light emitting device is determined notbelonging to any of the first color tone area, first through sixthregions, that light emitting device is dispatched into a seventh bin.

According to another embodiment of a method of manufacturing anillumination device, the light emitting devices are light emittingdiodes.

According to another embodiment of an illumination device manufacturingsystem, it includes: memory to store as a reference chromaticity data,the range of chromaticity for color tone sorting as a first color tonearea and a second color tone area, which is outside the first color tonearea, the second color tone area is divided into a first region, secondregion, third region, fourth region, fifth region, and sixth region, andthe first region and second region, the third region and fourth region,and the fifth region and sixth region are paired off to sandwich thefirst color tone area between the two regions of each pair; a firstcolor tone bin, first bin, second bin, third bin, fourth bin, fifth bin,and sixth bin established to correspond to each of the first color tonearea, and first through sixth regions; a color tone determining sectionto determine the color tone of each of the plurality of different colortone light emitting devices; a binning section to determine which of thefirst color tone area, and first through sixth regions each lightemitting device belongs to based on the color tone determined in thecolor tone determining section with reference to the referencechromaticity data stored in the memory, and based on thosedeterminations, dispatch each light emitting device into one of thefirst color tone bin and first through sixth bins; and a mountingsection to extract from the plurality of light emitting devices binnedin the first color tone bin, and first bin through the sixth bin, firstlight emitting devices from the first bin and second light emittingdevices from the second bin, and mount the extracted first lightemitting devices and second light emitting devices on a circuit boardwith disposition that results in merging and color-mixing the lightoutput from each light emitting device.

According to another embodiment of a method of binning light emittingdevices, the method including: determining a color tone of a pluralityof light emitting devices having different color tones; and binning thelight emitting devices into a first color tone area, a first region, asecond region, a third region, a fourth region, a fifth region, and asixth region depending on the determined color tone of each of the lightemitting device, the first color tone area being set on a chromaticitydiagram and a second color tone area that is outside the first colortone area being set on the chromaticity diagram in which the secondcolor tone area being further divided into the first region throughsixth region.

According to another embodiment of a method of binning light emittingdevices, the first region through sixth region are divided into pairs:the first region and the second region, the third region and the fourthregion, and the fifth region and the sixth region, such that each regionis positioned opposite its paired region on the other side of the firstcolor tone area.

According to another embodiment of a method of binning light emittingdevices, the first region through sixth region are regions defined by:vertices A, B, C of a triangle that inscribes the first color tone areaand is inscribed inside the second color tone area, which is concentricwith the first color tone area, and dividing lines AD, BE, CF that passthrough the center O of the second color tone area and divide the secondcolor tone area into six regions.

According to another embodiment of a method of binning light emittingdevices, the first region through sixth region are regions defined by:vertices A, B, C of a triangle that is inscribed inside the second colortone area and has sides that intersect with the perimeter of the firstcolor tone area at three or more points, and dividing lines AD, BE, CFthat pass through the center O of the second color tone area and dividethe second color tone area into six regions.

According to another embodiment of a method of binning light emittingdevices, two of the dividing lines extend in the long direction of thesecond color tone area.

According to another embodiment of a method of binning light emittingdevices, the first color tone area and the second color tone area haveelliptical shapes.

According to another embodiment of a method of binning light emittingdevices, the first color tone area is a 3-step MacAdam ellipse.

According to another embodiment of a method of binning light emittingdevices, the chromaticity diagram is a CIE x, y chromaticity diagram ora CIE LUV chromaticity diagram.

According to another embodiment of a method of binning light emittingdevices, light output from each of the light emitting devices is mergedand mixed to output white-light, and the center of the first color tonearea is positioned on or along the black-body locus, or towards thex-axis from the black-body locus.

According to another embodiment of a method of binning light emittingdevices, the light emitting devices are light emitting diodes.

First Embodiment

First, the method of binning light emitting devices for the firstembodiment of the present embodiment is described using FIG. 1. As shownin FIG. 1, a first color tone area 1 is defined in a given region of theCIE 1931 standard chromaticity diagram, which has x and y as horizontaland vertical axes (where x and y chromaticity coordinates are computedfrom the light power spectrum and spectral distribution coefficients).This first color tone area 1 is the desired color tone region for alight emitting device or for an illumination device that uses aplurality of light emitting devices. The first color tone area 1 for thefirst embodiment is essentially coincident with a 2.5-step MacAdamellipse centered at the x, y coordinates 0.3825, 0.3796 on thechromaticity diagram.

The outline of the first color tone area 1 is preferably a shape such asan ellipse (which is long in one direction and short in the otherdirection) or a polygon with long and short directions. Further, it isdesirable for the long direction to incline and align with the scatterin the light emitting device population due to process variation. Thisallows the number of light emitting devices selected within the firstcolor tone area 1 to be increased (increasing light emitting deviceyield in the first color tone area). As shown in FIG. 1, it is furtherdesirable for the first color tone area 1 to be an ellipse.

The location and size of the first color tone area defines a region (ofcolor space) where all the light emitting devices binned in that firstcolor tone area have the stipulated (targeted) color tone. For example,in the case of a light source for general lighting applications, it isdesirable for the first color tone area to be included inside one ANSIstandard chromaticity region (quadrilateral). Further, it is desirablefor the first color tone area to match or reside inside a MacAdamellipse, such as inside a 3-step MacAdam ellipse, centered at a specificchromaticity. It is even more desirable for the first color tone area toreside inside a 3-step MacAdam ellipse that lies inside a targeted colortone region such as inside one ANSI standard chromaticity region. Underthe above circumstance, by using only light emitting devices binned insuch first color tone area (without mixing or mounting any lightemitting devices binned in other color tone regions), illuminationdevices can be manufactured that all conform to the various standardsand/or appear to the human eye as the same color.

The center of the first color tone area can be at or in the vicinity ofthe following chromaticity coordinates: (x,y=0.4578, 0.4101),(x,y=0.4338, 0.4030), (x,y=0.4073, 0.3917), (x,y=0.3818, 0.3797),(x,y=0.3611, 0.3658), (x,y=0.3447, 0.3553), (x,y=0.3287, 0.3417), or(x,y=0.3123, 0.3282).

It should be mentioned that the interior of a 3-step MacAdam ellipseranges means within three standard deviations of color matching (SDMC).A MacAdam ellipse is the region of color space on a CIE standardchromaticity diagram with an outline that the human eye perceives asequidistant from a standard color tone. The MacAdam ellipse step size isthe number of SDMC. Said differently, the color tone of light producedby a light emitting device or illumination device with chromaticitycoordinates inside a 3-step MacAdam ellipse does not vary more thanthree SDMC from a given color.

MacAdam ellipses and SDMC are described in detail in references such as:MacAdam D. L., “Specification of Small Chromaticity Differences,”Journal of the Optical society of America, Vol. 33, No. 1, January 1943,pp. 18-26.

In case where the light emitting device or illumination device is onethat emits white-light, it is preferable for the first color tone area,and in particular in case where the perimeter of first color tone areais the MacAdam ellipse, to be centered along the black-body locus orslightly offset from the black-body locus towards the x-axis (away fromgreen color tones). This makes it possible to manufacture high-qualityillumination apparatus for general lighting applications.

In case where the perimeter of the first color tone area is effectivelycoincident with a MacAdam ellipse, it is preferable for the ellipse tobe a 3-step or smaller MacAdam ellipse, and more preferably for theellipse to be a 2.5-step or ≦2-step MacAdam ellipse. With these sizeMacAdam ellipses, and in particular with a 2-step or smaller MacAdamellipse, an extremely high-quality illumination device can be providedin which virtually no color variation can be perceived by the human eye.

The size of the first color tone area can also be set, for example, byproduction yield of light emitting devices. The first color tone area 1can be set to a region that encompasses the chromaticity of ≧50%≧75%≧80% of the light emitting devices manufactured.

The second color tone area 2 is a region of color-space outside thefirst color tone area 1. The second color tone area 2 of the presentembodiment has the outline of an ellipse that is larger than that of thefirst color tone area and specifically has the outline of 6-step MacAdamellipse.

The second color tone area 2 can have an arbitrary size and shape aslong as it lies outside the first color tone area 1. Specifically, thesecond color tone area 2 is formed as an annular shape that surroundsthe first color tone area 1.

The outline of the second color tone area 2 is preferably a shape suchas an ellipse (which is long in one direction and short in the otherdirection) or a polygon with long and short directions. In particular,an ellipse is the desired shape of the second color tone area 2. Asshown by the distribution of data points in FIG. 2, chromaticityvariation results when light emitting devices are manufactured usinglight emitting elements and phosphor (or fluorescent material) thatabsorbs light from the light emitting element and re-emits light at adifferent wavelength. As shown in FIG. 2, the distribution of datapoints on the chromaticity diagram takes on an approximately ellipticalshape with a major axis inclined in the direction of lines betweenpoints corresponding to the wavelength of light emitted from the lightemitting elements and points corresponding to the peak wavelength of thewavelength-conversion material (phosphor). Accordingly, by setting thesecond color tone area 2 along the distribution due to processvariation, it is possible to bin light emitting devices and utilize themin illumination devices without (reject) waste. Further, by setting theinclination of the second color tone area ellipse approaching theinclination of the process variation ellipse, the number of lightemitting devices binned in the second color tone area can approach thenumber binned in the first color tone area. This simplifies resourcefuluse light emitting devices without waste.

The second color tone area 2 preferably has a shape similar to that ofthe first color tone area 1. For example, when the first color tone area1 has an elliptical shape, it is desirable for the second color tonearea 2 to have an elliptical shape.

As shown in FIG. 1, the second color tone area 2 is divided into sixregions, which are a first region 51 through sixth region 56. Lightemitting devices for the first embodiment are binned by chromaticity inseven binning (selection) regions, which are the first region 51 throughsixth region 56 (at least six regions) of the color tone area, and thefirst color tone area 1.

The first region 51 is located opposite the second region 52 with thefirst color tone area 1 and center O of the second color tone area 2intervening in between. The third region 53 is located opposite thefourth region 54 with the first color tone area 1 and center O of thesecond color tone area 2 intervening in between. The fifth region 55 islocated opposite the sixth region 56 with the first color tone area 1and center O of the second color tone area 2 intervening in between.

In the present embodiment, the first region 51 through sixth region 56have shapes similar to pieces of an elliptical sector with verticestruncated along arcs on the perimeter of the first color tone area. Theoutline of the six regions are established by lines 31. 32, 33 thatintersect with the perimeter of the second color tone area 2 at threepoints D, E, F, pass through the center O of the second color tone area2, and intersect with the perimeter of the second color tone area 2 atthree other points A, B, C, which are the vertices of a triangle (brokenline in FIG. 1) inscribed inside the second color tone area 2 with sidesthat contact the perimeter of the first color tone area 1. Specifically,the outlines of the first region 51 through sixth region 56 includelines that connect to six intersection points on the perimeter and passthrough the center O of the second color tone area.

More specifically, the first region 51 is defined by an arc on theperimeter of the first color tone area 1, the first line 31 that passesthrough the center O of the second color tone area 2 and intersects withthe perimeter of the second color tone area 2 at the first vertex A ofthe triangle ABC (that circumscribes the first color tone area 1), thesecond line 32 that intersects with the perimeter of the second colortone area 2 at the second vertex B of the triangle and passes throughthe center O of the second color tone area 2, and the arc on theperimeter of the second color tone area 2 between the intersection pointE of the second line 32 with the perimeter of the second color tone area2 and the first vertex point A.

In the present specification, the lines 31, 32, 33 that pass through thecenter O of the second color tone area 2 and intersect with theperimeter of the second color tone area 2 at the vertices A, B, C of thetriangle, ABC which circumscribes the perimeter of the first color tonearea 1, are also called the dividing lines.

Although the present embodiment locates the dividing lines 31, 32, 33with respect to a triangle with vertices at points A, B, C, the trianglemay have an alternate disposition. For example, the triangle may haveits vertices at points D, E, F.

In the present embodiment, it is desirable for two of the dividing linesto be established extending in the long direction of the second colortone area. In particular, two of the dividing lines are preferablydisposed to scissor the major axis of the elliptical second color tonearea in between. This allows opposing binning regions to beapproximately symmetrical, makes it possible to bin approximately thesame number of light emitting devices in the opposing regions, andenables utilization of processed light emitting device without waste.

The ellipse inscribed inside the triangle indicates the range of colortone obtained by mixing light from light emitting devices binned in theopposing regions of the first through sixth regions. Specifically, whenlight emitting devices from the first and second regions, the third andfourth regions, or the fifth and sixth regions are used in combination,it is possible to obtain illumination device combined light emissionthat has color tone within the ellipse inscribed inside the triangle.Namely, by establishing this type of triangle that contacts theperimeter of the targeted color tone area (in other words, the firstcolor area 1), binning regions can be set to avoid wasting devices(described in detail later).

Binning region divisions can be set by dividing the second color tonearea 2 (outside the first color tone area 1) into six regions referencedto an inscribed triangle such that combined light from light emittingdevices binned in two of the six regions produces a color tone in thefirst color tone area. The method of binning light emitting devices bycolor tone can be a method that bins light emitting devices according tothe first color tone area and the second color tone area (outside thefirst color tone area), where the second color tone area is divided intoa first through sixth binning region. The outlines of the first throughsixth binning regions are fixed by the three vertices of a triangle,which is inscribed inside the second color tone area and intersects withthe first color tone area at three points or more, and three points onthe perimeter of the second color tone area that intersect with dividinglines that pass through the three vertex points of the triangle and thecenter of the second color tone area.

(Second Embodiment)

For example, at least one side of the triangle may intersect with theoutline of the first color tone area at two points. As shown in FIG. 3,when the first color tone area is established as a 3-step MacAdamellipse and the second color tone area as a 5-step MacAdam ellipse, atriangle inscribed inside the second color tone area is smaller than onethat inscribes the first color tone area and each side intersects withthe perimeter of the first color tone area at two points. When the firstcolor tone area 1, second color tone area 2, and first region 51 throughsixth region 56 are set in this manner, light from an illuminationdevice using devices binned in the second color tone area 2 will beinside the first color tone area 1 and inward from its boundary with thesecond color tone area 2. This allows manufacture of illuminationdevices that emit light of the targeted color tone even when sorting(binning) accuracy is not very high. For example, if light emittingdevices binning is not highly accuracy (relatively large sorting error),the error can be absorbed and the targeted color can still be achieved.The size of the (reference) triangle can be suitably chosen depending onbinning accuracy and the required quality of the illumination device.However, if the triangle is too small, namely if the second color tonearea is small, the color tone area for usable light emitting devicesbecomes small. In this respect, it is desirable for the triangle toinscribe (have sides tangent to) the first color tone area and beinscribed inside the second color tone area, as shown in FIG. 1. Thisallows light emitting device binning to minimize wasted (reject)devices.

Note, in the present application, terms such as “inscribed,” “inscribedinside,” “centered at,” “through the center,” and “inside a region” donot necessarily have the meaning associated with narrow definition, andcan include wider meanings accepted as essentially the same in practice.The range of meaning can also include deviation or error such as thatdue to variation in device measurement and processing tool settings.

The first color tone area 1, the second color tone area 2, and the firstregion 51 through the sixth region 56 can be established by anyarbitrary method as long as it does not deviate from the intent impliedby previous description. There is no particular requirement to initiallyestablish a triangle, and the dividing lines 31, 32, 33 may be generatedbased on computation alone. For example, two concentric circles can beestablished with three lines angularly separated by 60° passing throughthe common center point, the eccentricity of the circles can beincreased while inclining the major axis, those inner and outer ellipsesoverlaid on a chromaticity diagram can be designated as the first colortone area 1 and the second color tone area 2 with the three linesforming the dividing lines 31, 32, 33.

Light emitting devices are binned (sorted) according to the binningregions described above. The light emitting devices can be binned byaccepted (well-known within the industry) binning methods. For example,the binning process can supply power to a light emitting device bycontacting measurement equipment probes to the positive and negativeelectrodes of the device, and the color tone of light emitted from thedevice can be measured.

In this manner, a plurality of light emitting devices are binned in thefirst color tone area 1, first region 51 through sixth region 56. Thebinned light emitting device is kept as either group of the first colortone area 1, first region 51 through sixth region 56, respectively. Forexample, each light emitting device is sorted into container, bin or bagcorresponding to the first color tone area 1, first through sixthregions. By mounting light emitting devices, which are binned in thismanner, according to the mounting method described below, anillumination device can be manufactured that emits light having colortone within the first color tone area. The bins can be cylindricalcontainers, boxes, or trays divided into a plurality of sections, e.g.Depending on requirements, light emitting devices sorted into thesetypes of bins can be bagged or transferred into other types ofcontainers.

A method of mounting is descried for the case where light emittingdevices binned in the first region 51 (FIG. 1) and in the second region52, which is opposite the first region 51 on the other side of the firstcolor tone area 1, are mounted in an illumination device.

When the light flux of each light emitting device is the same, mountinga light emitting device with chromaticity at the boundary point A of thefirst region 51 and a light emitting device with chromaticity at theboundary point B of the second region 52 results in an illuminationdevice that produces light with a chromaticity at the tangent point L1of the triangle with the perimeter of the first color tone area 1.Similarly, an illumination device using light emitting devices withchromaticity at boundary points E and D produces light with achromaticity at point L2 on the perimeter of the first color tone area1.

Specifically, if the amount of light emitted from light emitting devicesbinned in the first region 51 and second region 52 is the same (if thelight flux and number of devices is the same), the color tone of theresulting illumination device will be on the perimeter or inside thefirst color tone area 1 even when the most boundary-case devices aremounted, and the targeted color tone can be achieved. It should bementioned that in actual light emitting device manufacture, the numberof devices with chromaticity on the boundary of a binning region may notbe large, and in practice the chromaticity of resulting illuminationdevices is inward from the perimeter of the first color tone area.

In this manner, an illumination device that emits light having thechromaticity of the first color tone area 1 can be manufacturedefficiently using light emitting devices that emit light within a widerrange of chromaticity (outside the first color tone area).

Establishing fine subdivisions of light emitting device color tonebinning regions may increase cost and lower yield. However, with thebinning method of the present embodiment, binned light emitting devicescan be utilized without waste, and illumination devices with thetargeted color tone can be produced. Further, the number of lightemitting devices rejected for emission with chromaticity outside thetargeted range can be reduced.

Although an example of light emitting devices binned in the first region51 and in the second region 52 is described here, light emittingdevices, i.e., third light emitting devices 10 c and fourth lightemitting devices 10 d respectively binned in the third region 53 and inthe fourth region 54 (which is opposite the third region 53 on the otherside of the first color tone area 1), or light emitting devices, i.e.,fifth light emitting devices 10 e and sixth light emitting devices 10 frespectively binned in the fifth region 55 and in the sixth region 56(which is opposite the fifth region 55 on the other side of the firstcolor tone area 1) can also be used in illumination devices that emitlight with color tone in the first color tone area 1. Further, it shouldbe noted that first color tone area light emitting device 10 o which arebinned in the first color tone area 1 need not to combine other lightemitting devices binned in other area, but are employed alone to achieveillumination device outputting desired color tone light.

The method of mounting light emitting devices preferably alternatelymounts light emitting devices binned in different regions one by one orgroup by group (for a plurality of devices). When devices are mounted ina plurality of rows, it is desirable for light emitting devices binnedin one region to be adjacent to light emitting devices binned in adifferent region. This can increase color mixing of light emitted bydevices binned in different regions, and can produce light withapproximately uniform color over the entire light emitting area of theillumination device.

(Light Emitting Device)

A cross-section drawing of one example of a light emitting devicesuitable for use in the present embodiment is shown in FIG. 4. Forexample, the light emitting device 10 has a light emitting element 11mounted inside a recessin the package 13, and has light transmittingencapsulating material 14 encasing the light emitting element 11. Thelight emitting element 11 and positive and negative electrodes 12(leads) exposed from the bottom of the package are electricallyconnected via two bonding wires 15. Further, the light transmittingencapsulating material 14 contains phosphor 16.

Devices such as a surface mounted type light emitting diode (LED), whichhouses the light emitting element inside a package provided withpositive and negative electrodes and reflecting material etc., adomed-top (lamp type) LED, and a chip-scale package LED, which has resinmaterial and phosphor etc. integrally formed around the light emittingelement, can be used as light emitting devices.

The light emitting element has, for example, a p-type semiconductorlayer, an active region that emits light, an n-type semiconductor layer,a p-side electrode electrically connected to the p-type semiconductorlayer, and an n-side electrode electrically connected to the n-typesemiconductor layer. Electrodes of light emitting element areelectrically connected to (package) lead electrodes by techniques suchas die-bonding, wire-bonding, or flip-chip bonding. Electrodes of lightemitting element can also be exposed outside the light emitting deviceas lead electrodes for surface-mount connection to a circuit board.

The emission wavelength and material used for a light emitting elementcan be, for example, in the case of a blue or violet light emittingelement, GaN-based semiconductor material deposited on a sapphiresubstrate. This light emitting element can be combined with phosphor(described below) to manufacture a white-light emitting device in astraight-forward manner.

(Phosphor)

The light emitting device may not only include a light emitting element,but may also include phosphor (or fluorescent material) that absorbs theemitted light and re-emits it at a different wavelength. This makes thelight emitted from a light emitting device a combination of lightemission from the light emitting element and from the phosphor.

Phosphor can be disposed in the light emitting device by variousmethods. For example, phosphor can be mixed into the light transmittingencapsulating material that surrounds the light emitting element, or itcan be disposed above the light emitting element in sheet-like form.

Various materials that can absorb light emitted from a light emittingelement and re-emit light at a different wavelength can be used as thephosphor. For example, the phosphor can be nitride and oxy-nitridesystem phosphors primarily activated by lanthanoid-group elements suchas europium and cerium. More specifically, the phosphor can besubstances such as europium-activated α or β-sialon (β-SiAlON) phosphor,various alkaline earth metal nitride silicate phosphors,lanthanoid-group elements such as europium, alkaline earth metalhalogen-apatite phosphors primarily activated by transition metal groupelements such as manganese, alkaline earth halo-silicate phosphors,alkaline earth metal silicate phosphors, alkaline earth metal halogenborate phosphors, alkaline earth metal aluminate phosphors, alkalineearth metal silicates, alkaline earth metal sulfides, alkaline earthmetal thiogallates, alkaline earth metal silicon nitride, germinate,rare earth element aluminates primarily activated by lanthanoid-groupelements such as cerium, and organic and organic complex materialsprimarily activated by rare earth element silicates or lanthanoid-groupelements such as europium. In particular, for the case of use incombination with a blue light emitting element, yellow fluorescingyttrium-aluminum-garnet (Y₃Al₅O₁₂: YAG) based phosphor, red fluorescingCaAlSiN₃ (CASN) and K₂SiF₆ (KSF), and green fluorescing β-SiAlON andlutetium-aluminum-garnet (Al₅Lu₃O₁₂: LAG) can be with good results. Thisallows manufacture of light emitting devices with color tone from whiteto incandescent light.

It is possible to use two or more types of phosphor in a single lightemitting device. Two or more phosphor types can be used by mixing themtogether or by disposing them in layers.

Color variation for light emitting devices using two or more types ofphosphor, which fluoresce with different colors, is greater than thatfor devices using a single type of phosphor. For example, a lightemitting device that emits white-light can be manufactured using a bluelight emitting element and two types of phosphor that absorb blue lightand re-emit green and red light respectively. In that case, variation inphosphor quantity or mixing ratio results in light emitting devices withcolor tone having a wide distribution in two directions in color space(in the green y-direction and red x-direction on the chromaticitydiagram). Namely, the range of light emitting device color tonevariation is greater than that for the case of a single type ofphosphor. However, even for this case of wider color tone variation,illumination devices that produce the desired color tone can bemanufactured and cost reduced by implementing the color tone binningmethod of the present embodiment.

Also in the case of phosphor color variation that extends in twodirections, it can be difficult to fit the light emitting device colortone distribution to the slope and shape of the black-body locus orMacAdam ellipse. Consequently, there may be a tendency for number oflight emitting devices binned in the first color tone area 1 to decreaseand reduce yield. However, in the present embodiment, light emittingdevices are used that have color tone in the second color tone area 2,which is outside the first color tone area 1, and illumination devicescan be manufactured with the desired color tone while reducingillumination device manufacturing and color tone binning costs.

For the same reasons described above, color tone variation is alsoincreased when different types of phosphor are formed in layers. In thiscase as well, application of the methods of the present embodiment hassimilar advantageous results.

In addition, the light emitting device can carry a plurality of lightemitting elements that emit different colors without including phosphor.Devices that carry a plurality of different color light emittingelements and include phosphor are also possible. Specifically, a lightemitting device using a blue light emitting element and phosphor thatabsorbs blue light and re-emits green light can produce a light-green(whitish green) color. Light from that device can be merged with lightfrom a red light emitting element or a light emitting device thatincludes a red light emitting element to make a light emitting devicethat produces light within the white-light region of color space. Inthis case, light emitting device color tone binning can be performed atthe light-green stage, or after merging with light from red lightemitting elements.

Variation (dispersion) in light emitting device color tone has variouscauses. For example, there can be variation in phosphor quantity anddistribution, light emitting element emission wavelength, phosphormixing ratio, viscosity of the resin that includes phosphor, and in therun-time wear or various manufacturing and measurement equipment.

(Illumination Device)

The illumination device for the present embodiment can be any type oflighting device. For example, the illumination device can be backlightfor equipment such as a television set or smart phone, a light-bulbshaped light (as shown in FIG. 5 for example), fluorescent light shapedlighting, recessed troffer fixture lighting, spotlight lighting, linearfixture lighting, street lighting, an automotive headlight, or aflashlight. The light-bulb shaped illumination device 100 shown in FIG.5 has a plurality of light emitting devices 10 surface mounted on acircuit board 18.

Light emitting device binning method and illumination devicemanufacturing method are described above to illustrate embodiment of thepresent invention. However, it should go without saying that the presentinvention is not limited to embodiment as described above, and based onthe previous descriptions, various modifications or improvements arealso included within the intent of the present invention.

Third Embodiment

For example, although previous description is based on the CIE 1931standard chromaticity diagram, the present embodiment can also beapplied in the case of other chromaticity diagram formats. For example,the present embodiment can be applied as well to the u′, v′ coordinatechromaticity diagram (CIE 1976 or CIELUV color space) shown in FIG. 7.Here, the first color tone area 1 essentially coincides with a 3-stepMacAdam ellipse (in the same manner as in the second embodiment), andthe second color tone area 2 is divided by three dividing lines 31, 32,33 into six binning regions, which are the first region 51 through thesixth region 56.

Further, there is no requirement for light emitting device binning to beimplemented only once. After sorting devices into bins that are finerthan the six regions, devices from a plurality of regions can becombined and used as one wider region. Conversely, after initial binninginto wide regions, devices can be re-sorted into narrower regions.

Light emitting devices binned into three or more regions can be used inproducing the illumination device.

Fourth Embodiment

Further, as shown in FIG. 6, a third color tone area 21, which is largerthan the second color tone area 2 can also be established. Here, thethird color tone area 21 can be divided into regions by extending thedividing lines 31, 32, 33 set to divide the second color tone area 2.According to an example shown in FIG. 6, the second color tone area 2 isdivided into six regions of the first through sixth regions 51 to 56,and the third color tone area 21 is also divided into six regions of afirst region 61, second region 62, third region 63, fourth region 64,fifth region 65, and sixth region 66 by the dividing lines 31, 32 and 33in the same manner as the second color tone area 2 setting the firstthrough sixth regions 51 to 56.

(Illumination Device Manufacturing System 1000)

FIG. 12 shows an illumination device manufacturing system 1000 foranother embodiment. The illumination device manufacturing system 1000shown in this figure is provided with a color tone determining section71, a binning section 72, memory 73, container bins 74, and a mountingsection 75. The color tone determining section 71 includes equipment todetect the color tone of the plurality of different color tone lightemitting devices. As described previously, equipment well-known in theindustry is used to contact measurement probes to the positive andnegative electrode (leads) of each light emitting device and supplypower to activate light emission and measure color tone.

The binning section 72 includes hardware for sorting the light emittingdevices 10 according to the color tone measured in the color tonedetermining section 71. Light emitting devices 10 sorted by color toneare retained in container bins 74. The binning section 72 is coupledwith memory 73, and chromaticity reference data is pre-stored in memory73. Chromaticity reference data includes information defining regiondivisions on the chromaticity diagram such as those shown in FIG. 1(described previously). The range of chromaticity for sorting is set tothe first color tone area 1 and the second color tone area 2, which isoutside the first color tone area 1. The second color tone area 2 isdivided into the first region 51, the second region 52, the third region53, the fourth region 54, the fifth region 55, and the sixth region 56.Further, the first region 51 and the second region 52, the third region53 and the fourth region 54, and the fifth region 55 and the sixthregion 56 are paired off to sandwich the first color tone area 1 betweenthe two regions of each pair.

The container bins 74 are retainers to hold light emitting devices 10sorted by the binning section 72. A first color tone bin 74 o, first bin74 a, second bin 74 b, third bin 74 c, fourth bin 74 d, fifth bin 74 e,and sixth bin 74 f are prepared corresponding to each of seven regions(the first color tone area, first region through the sixth region). Thefirst color tone bin is provided to hold light emitting devices withchromaticity within the first color tone area (within illuminationdevice specifications). It is also possible to further divide the firstbin 74 a through the sixth bin 74 f such that each bin has subdivisions.For example, even for light emitting devices having same color tone,they can be further sorted based on other parameter such as output orforward voltage of the device. In addition, the first color tone bincorresponding to the first color tone area may be further divided assub-bins to sort more specifically. As such, each area or regions andbins correspond not only one-to-one respectively, but also the first bin74 a through the sixth bin 74 f corresponding to the first through sixthregion can be further divided. Additionally, other than such first bin74 a through the sixth bin 74 f, a seventh bin can be provided to holdlight emitting devices that have color tone not within any of the sixregions (or inside the first color tone area). Light emitting devicesbinned in the seventh bin can be rejected as out-of-specification, forexample. Cylindrical jars, boxes, bags, or other receptacles ofarbitrary shape can be used as the container bins.

The binning section 72 determines which region (of the first throughsixth regions) each light emitting device 10 belongs to based on thecolor tone detected by the color tone determining section 71 withreference to the reference chromaticity data stored in memory 73. Basedon binning determination results, each light emitting device 10 isdispatched into one of the container bins (first bin 74 a through thesixth bin 74 f). Although the above-described embodiments sort lightemitting devices having variety of color tones into either the firstcolor tone bin 74 o, first bin 74 a, second bin 74 b, third bin 74 c,fourth bin 74 d, fifth bin 74 e, or sixth bin 74 f by single sortingstep, the present invention does not limited to such configuration,rather it may perform sorting step by several sub-steps. For example, itmay perform initial determination to parent population of light emittingdevices, whether each of which belongs to either the first color tonearea 1 or second color tone area 2, then perform another determinationto the initially sorted population belonging to the second color tonearea 2, further belongs to either first region 51 through sixth region56. Even such sorting or binning method to population which is alreadysorted or filtered thus confirmed as the second color tone 2 should becovered by the embodiment of the present invention of sorting method oflight emitting device or manufacturing method of illumination device.

The mounting section 75 matches-up light emitting devices 10 held in thecontainer bins 74 and mounts them on a circuit board for illuminationdevice assembly. Specifically, from the plurality of light emittingdevices 10 binned in the first bin 74 a through the sixth bin 74 f,first light emitting devices 10 a from the first bin 74 a and secondlight emitting devices 10 b from the second bin 74 b are extracted andmounted on a circuit board with orientation that results in merging (andcolor-mixing) of light output from the first light emitting devices 10 aand the second light emitting devices 10 b. Similarly, third lightemitting devices 10 c from the third bin 74 c and fourth light emittingdevices 10 d from the fourth bin 74 d are extracted and mounted on acircuit board with orientation that results in merging (andcolor-mixing) of light output from the third light emitting devices 10 cand the fourth light emitting devices 10 d. Finally, fifth lightemitting devices 10 e from the fifth bin 74 e and sixth light emittingdevices 10 f from the sixth bin 74 f are extracted and mounted on acircuit board with orientation that results in merging (andcolor-mixing) of light output from the fifth light emitting devices 10 eand the sixth light emitting devices 10 f. Light emitting device layoutand the number of devices mounted on the circuit board are appropriatelydesigned according to illumination device requirements such as outputand lighting configuration.

Logistic flow between the measurement section 71, a binning section 72,container bins 74, and a mounting section 75 can be direct or thosesections can be physically, spatially, or temporally separated. Forexample, light emitting devices can be first removed from the bins andbagged, and then transported to a separate assembly facility formounting. In that case, the container bins and mounting section are inseparated locations. Also, a binning section and mounting section may beprovided in the separate equipment.

The following describes one example of a technique for assembling aplurality of different color light emitting devices to obtain anillumination device that produces merged light within a targetedchromaticity range such as within a 3-step MacAdam ellipse. Turning toFIG. 10, 3-step MacAdam ellipse and 5-step MacAdam ellipse areas areshown plotted on a CIE (Commission Internationale de l'eclairage) 1931(x, y) standard chromaticity diagram. In this figure, the inner ellipseOV1 delineates the area of a 3-step MacAdam ellipse and the outerellipse OV2 delineates the area of a 5-step MacAdam ellipse. By plottingthe chromaticity x, y coordinates for many light emitting devices onthis diagram (graph), a distribution is obtained. For example, bycontacting measurement probes to the positive and negative electrode(leads) of each light emitting device and supplying power, the colortone of the emitted light can be measured to obtain x, y chromaticitycoordinates and establish a chromaticity distribution. Light emittingdevices with coordinates inside the inner ellipse OV1 (shown incross-hatched) satisfy conditions of the 3-step MacAdam ellipse and canbe used as single units. However, light emitting devices withcoordinates outside the inner ellipse OV1 do not satisfy 3-step MacAdamellipse conditions and cannot be used individually. To avoid rejectingand efficiently utilize those (outlier) devices, a plurality ofdifferent color tone light emitting devices can be used together toproduce merged (color-mixed) light that has chromaticity within theinner ellipse OV1. As a specific case, the annular region between theinner ellipse OV1 and the outer ellipse OV2 is divided into foursections. For example, if the annular region is divided (clockwise) intoa first region 91, a third region 93, a second region 92, and a fourthregion 94, each opposing pair of regions, which are the first region 91and the second region 92, and the third region 93 and the fourth region94, is disposed with the 3-step MacAdam ellipse area intervening inbetween. Light emitting devices distributed within the annular regionsub-divided in this manner are graded and binned as either in the firstregion 91, second region 92, third region 93, or fourth region 94.Ultimately, when illumination devices are constructed, light emittingdevices binned in opposing regions are assembled together. For example,while light emitting devices binned in the first region 91 and thesecond region 92 are each (individually) outside the 3-step MacAdamellipse, their merged light can be between the first region 91 and thesecond region 92 and within the 3-step MacAdam ellipse. Similarly, lightemitting devices binned in the third region 93 and the fourth region 94can be assembled together in an illumination device with merged lighthaving chromaticity between those regions and within the intervening3-step MacAdam ellipse. This technique allows light emitting devicesoutside the targeted 3-step MacAdam ellipse to be used to obtain anillumination device that outputs light within a given range ofchromaticity.

However, illumination devices produced by this technique have thedrawback that they do not necessariy output light with chromaticityinside the 3-step MacAdam ellipse. Specifically, light emitting devicesare simply binned into the first region 91 through the fourth region 94,and location within each region is unknown. Accordingly, randomlyselected devices from those binned in the first region 91 and the secondregion 92 may produce merged light that is not within the 3-step MacAdamellipse. For example, as shown in FIG. 11, if light emitting devicechromaticity coordinates are at the points RA and RB, their merged lightchromaticity is at the point RX on the line joining RA and RB (outsidethe 3-step MacAdam ellipse). Similarly, if light emitting devices withchromaticity at points RC and RD are assembled together, their mergedlight chromaticity is at the point RY on the line joining those pointsand not within the 3-step MacAdam ellipse. In these types ofabove-mentioned light emitting device binning schemes, illuminationdevice output may deviate from the targeted chromaticity depending onwhich binned devices are assembled together. This results in variationin quality of the illumination devices produced, To avoid this outcome,operations can be considered such as recording information indicatingthe position of each light emitting device within the chromaticitydistribution, pre-calculating color tone for merged light from anillumination device using selected light emitting devices, andeliminating device combinations that produce light outside the 3-stepMacAdam ellipse. However, this makes it necessary to record chromaticityinformation for an enormous number of light emitting devices, is verylabor-intensive, leads to system complexity, and increases cost.Alternatively, narrowing the divisions of the annular region can beconsidered. In that case, the binning regions become smaller reducingthe number of usable light emitting devices, and this increases cost byrequiring additional sorting or device rejection. Consequently, a simplebinning method that can keep illumination device output light within thetargeted chromaticity range is in demand.

One aspect of the embodiment of the present invention is a method ofmanufacturing an illumination device that can include a step to preparea plurality of light emitting devices having different color tones; anda step that establishes on a chromaticity diagram (for binning purposes)a first color tone area and a second color tone area that is outside thefirst color tone area, further divides the second color tone area into afirst region through sixth region, detects the color tone of theprepared plurality of different color tone light emitting devices, andbins (sorts) the light emitting devices into the first region throughsixth region depending on color tone.

Another aspect of the embodiment of the present invention is a method ofbinning light emitting devices that can include a step to prepare aplurality of light emitting devices having different color tones; and astep that establishes on a chromaticity diagram (for binning purposes) afirst color tone area and a second color tone area that is outside thefirst color tone area, further divides the second color tone area into afirst region through sixth region, detects the color tone of theprepared (plurality of) different color tone light emitting devices, andbins (sorts) the light emitting devices into the first region throughsixth region depending on color tone.

This makes it possible to provide a lower cost method of binning bycolor tone and method of illumination apparatus manufacture.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

It should be apparent to those with an ordinary skill in the art thatwhile various embodiments of the invention have been shown anddescribed, it is contemplated that the invention is not limited to theparticular embodiments disclosed, which are deemed to be merelyillustrative of the inventive concepts and should not be interpreted aslimiting the scope of the invention, and which are suitable for allmodifications and changes falling within the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. A method of manufacturing an illumination device,comprising: detecting a color tone of each of a plurality of lightemitting devices having different color tones; determining the colortone of each of the plurality of light emitting devices is in whichregion among a first region, a second region, a third region, a fourthregion, a fifth region, and a sixth region on a chromaticity diagrambased on the detected color tone, the chromaticity diagram having afirst color tone area and a second color tone area in which the firstcolor tone area is provided, the second color tone area being dividedinto the first region through the sixth region; and classifying theplurality of light emitting devices into the first region through thesixth region based on the determined color tone.
 2. The method accordingto claim 1, wherein the first region and the second region are providedopposite to each other to sandwich the first color tone area between thefirst region and the second region on the chromaticity diagram, whereinthe third region and the fourth region are provided opposite to eachother to sandwich the first color tone area between the third region andthe fourth region on the chromaticity diagram, and wherein the fifthregion and the sixth region are provided opposite to each other tosandwich the first color tone area between the fifth region and thesixth region on the chromaticity diagram.
 3. The method according toclaim 2, further comprising: mounting at least one first light emittingdevice among the plurality of light emitting devices which is classifiedin the first region and at least one second light emitting device amongthe plurality of light emitting devices which is classified in thesecond region with disposition to merge and mix light output from the atleast one first light emitting device and the at least one second lightemitting device.
 4. The method according to claim 2, further comprising:mounting at least one third light emitting device among the plurality oflight emitting devices which is classified in the third region and atleast one fourth light emitting device among the plurality of lightemitting devices which is classified in the fourth region withdisposition to merge and mix light output from the at least one thirdlight emitting device and the at least one fourth light emitting device.5. The method according to claim 2, further comprising: mounting atleast one fifth light emitting device among the plurality of lightemitting devices which is classified in the fifth region and at leastone sixth light emitting device among the plurality of light emittingdevices which is classified in the sixth region with disposition tomerge and mix light output from the at least one fifth light emittingdevice and the at least one sixth light emitting device.
 6. The methodaccording to claim 1, wherein the first region through the sixth regionare regions defined by vertices A, B, and C of a triangle that inscribesthe first color tone area and is inscribed inside the second color tonearea having a same center with the first color tone area and dividinglines AD, BE, and CF that pass through a center O of the second colortone area and divide the second color tone area into six regions.
 7. Themethod according to claim 1, wherein the first region through the sixthregion are regions defined by vertices A, B, and C of a triangle that isinscribed inside the second color tone area and has sides that intersectwith a perimeter of the first color tone area at three or more pointsand dividing lines AD, BE, and CF that pass through a center O of thesecond color tone area and divide the second color tone area into sixregions.
 8. The method according to claim 6, wherein two of the dividinglines AD, BE, and CF extend in a longitudinal direction of the secondcolor tone area.
 9. The method according to claim 1, wherein the firstcolor tone area and the second color tone area have elliptical shapes.10. The method according to claim 1, wherein the first color tone areaaccords with a 3-step MacAdam ellipse.
 11. The method according to claim1, wherein the chromaticity diagram comprises a CIE x, y chromaticitydiagram or a CIE LUV chromaticity diagram.
 12. The method according toclaim 1, wherein light output from each of the plurality of lightemitting devices is merged and mixed to output white-light, and whereina center of the first color tone area is positioned on or along ablack-body locus, or towards a x-axis from the black-body locus.
 13. Themethod according to claim 1, wherein a reference chromaticity dataincluding a range of chromaticity for color tone classifying on thechromaticity diagram is stored in memory, wherein the range ofchromaticity includes the first color tone area and the second colortone area in which the first color tone area is provided, and the secondcolor tone area is divided into the first region, the second region, thethird region, the fourth region, the fifth region, and the sixth region,wherein the first region and the second region are provided opposite toeach other to sandwich the first color tone area between the firstregion and the second region, wherein the third region and the fourthregion are provided opposite to each other to sandwich the first colortone area between the third region and the fourth region, wherein thefifth region and the sixth region are provided opposite to each other tosandwich the first color tone area between the fifth region and thesixth region, wherein in determining the color tone, the referencechromaticity data stored in the memory is referred to determine thecolor tone of each of the plurality of light emitting devices is inwhich area or region among the first color tone area, the first region,the second region, the third region, the fourth region, the fifthregion, and the sixth region based on the detected color tone, whereinthe method comprises dispatching each of the plurality of light emittingdevices into one of a first color tone bin, a first bin, a second bin, athird bin, a fourth bin, a fifth bin, and a sixth bin which are providedto respectively correspond to the first color tone area and the firstregion through the sixth region based on the determined color tone, andwherein the method comprises extracting first light emitting devicesamong the plurality of light emitting devices and second light emittingdevices among the plurality of light emitting devices from the first binand the second bin, respectively, wherein the method comprises mountingthe first light emitting devices and the second light emitting deviceson a circuit board with disposition to merge and mix light output fromthe first light emitting devices and the second light emitting devices.14. The method according to claim 13, further comprising: dispatchingone light emitting device among the plurality of light emitting devicesinto a seventh bin if the one light emitting device is determined notbelonging to any one of the first color tone area and the first regionthrough the sixth region.
 15. The method according to claim 1, whereinthe plurality of light emitting devices comprise light emitting diodes.16. An illumination device manufactured by a method comprising:detecting a color tone of each of a plurality of light emitting deviceshaving different color tones; determining the color tone of each of theplurality of light emitting devices is in which region among a firstregion, a second region, a third region, a fourth region, a fifthregion, and a sixth region on a chromaticity diagram based on thedetected color tone, the chromaticity diagram having a first color tonearea and a second color tone area in which the first color tone area isprovided, the second color tone area being divided into the first regionthrough the sixth region; and classifying the plurality of lightemitting devices into the first region through the sixth region based onthe determined color tone.
 17. An illumination device manufacturingsystem comprising: memory to store a reference chromaticity dataincluding a range of chromaticity for color tone classifying whichincludes a first color tone area and a second color tone area in whichthe first color tone area is provided, the second color tone area beingdivided into a first region, a second region, a third region, a fourthregion, a fifth region, and a sixth region, the first region and thesecond region being provided opposite to each other to sandwich thefirst color tone area between the first region and the second region,the third region and the fourth region being provided opposite to eachother to sandwich the first color tone area between the third region andthe fourth region, the fifth region and the sixth region being providedopposite to each other to sandwich the first color tone area between thefifth region and the sixth region; a first color tone bin, a first bin,a second bin, a third bin, a fourth bin, a fifth bin, and a sixth binwhich are provided to respectively correspond to the first color tonearea and the first region through the sixth region; a color tonedetector configured to detect a color tone of each of a plurality ofdifferent color tone light emitting devices; a classifying deviceconfigured to determine which of the first color tone area and the firstregion through the sixth region each of the plurality of different colortone light emitting devices belongs to based on the color tone detectedby the color tone detector with reference to the reference chromaticitydata stored in the memory so as to dispatch each of the plurality ofdifferent color tone light emitting devices into one of the first colortone bin and the first bin through the sixth bin; and a mounting deviceconfigured to extract from the plurality of different color tone lightemitting devices dispatched in the first color tone bin and the firstbin through the sixth bin first light emitting devices in the first binand second light emitting devices in the second bin, and configured tomount the first light emitting devices and the second light emittingdevices on a circuit board with disposition to merge and mix lightoutput from the first light emitting devices and the second lightemitting devices.
 18. A method of classifying color tone of lightemitting devices, comprising: classifying each of a plurality of lightemitting devices having different color tones into a first region, asecond region, a third region, a fourth region, a fifth region, and asixth region in a color tone area including a first color tone area anda second color tone area in which the first color tone area is provided,the second color tone area being divided into the first region, thesecond region, the third region, the fourth region, the fifth region,and the sixth region, outlines of the first region through the sixthregion being defined by first three points of intersection on aperimeter of the second color tone area at which a trianglecircumscribed outside the first color tone area intersects with theperimeter of the second color tone area and second three points ofintersection on the perimeter of the second color tone area at whichdividing lines that pass through the first three points of intersectionand a center of the second color tone area intersect with the perimeterof the second color tone area.
 19. A method of classifying lightemitting devices, comprising: detecting a color tone of each of aplurality of light emitting devices having different color tones;determining the color tone of each of the plurality of light emittingdevices is in which region among a first region, a second region, athird region, a fourth region, a fifth region, and a sixth region on achromaticity diagram based on the detected color tone, the chromaticitydiagram having a first color tone area and a second color tone area inwhich the first color tone area is provided, the second color tone areabeing divided into the first region through the sixth region; andclassifying the plurality of light emitting devices into the firstregion through the sixth region based on the determined color tone. 20.The method according to claim 19, wherein the first region and thesecond region are provided opposite to each other to sandwich the firstcolor tone area between the first region and the second region on thechromaticity diagram, wherein the third region and the fourth region areprovided opposite to each other to sandwich the first color tone areabetween the third region and the fourth region on the chromaticitydiagram, and wherein the fifth region and the sixth region are providedopposite to each other to sandwich the first color tone area between thefifth region and the sixth region on the chromaticity diagram.
 21. Themethod according to claim 19, wherein the first region through the sixthregion are regions defined by vertices A, B, and C of a triangle thatinscribes the first color tone area and is inscribed inside the secondcolor tone area having a same center with the first color tone area anddividing lines AD, BE, and CF that pass through a center O of the secondcolor tone area and divide the second color tone area into six regions.22. The method according to claim 19, wherein the first region throughthe sixth region are regions defined by vertices A, B, and C of atriangle that is inscribed inside the second color tone area and hassides that intersect with a perimeter of the first color tone area atthree or more points, and dividing lines AD, BE, and CF that passthrough a center O of the second color tone area and divide the secondcolor tone area into six regions.
 23. The method according to claim 21,wherein two of the dividing lines AD, BE, and CF extend in alongitudinal direction of the second color tone area.
 24. The methodaccording to claim 19, wherein the first color tone area and the secondcolor tone area have elliptical shapes.
 25. The method according toclaim 19, wherein the first color tone area accords with a 3-stepMacAdam ellipse.
 26. The method according to claim 19, wherein thechromaticity diagram comprises a CIE x, y chromaticity diagram or a CIELUV chromaticity diagram.
 27. The method according to claim 19, whereinlight output from each of the plurality of light emitting devices ismerged and mixed to output white-light, and wherein a center of thefirst color tone area is positioned on or along a black-body locus, ortowards a x-axis from the black-body locus.
 28. The method according toclaim 19, wherein the plurality of light emitting devices comprise lightemitting diodes.
 29. A method of manufacturing an illumination device,comprising: manufacturing the illumination device using a plurality oflight emitting devices classified by a method comprising: classifyingeach of the plurality of light emitting devices having different colortones into a first region, a second region, a third region, a fourthregion, a fifth region and a sixth region in a color tone area includinga first color tone area and a second color tone area in which the firstcolor tone area is provided, the second color tone area being dividedinto the first region, the second region, the third region, the fourthregion, the fifth region and the sixth region, outlines of the firstregion through the sixth region being defined by first three points ofintersection on a perimeter of the second color tone area at which atriangle circumscribed outside the first color tone area intersects withthe perimeter of the second color tone area and second three points ofintersection on the perimeter of the second color tone area at whichdividing lines that pass through the first three points of intersectionand a center of the second color tone area intersect with the perimeterof the second color tone area.
 30. An illumination device manufacturedby a method comprising: manufacturing the illumination device using aplurality of light emitting devices classified by a method comprising:classifying each of the plurality of light emitting devices havingdifferent color tones into a first region, a second region, a thirdregion, a fourth region, a fifth region and a sixth region in a colortone area including a first color tone area and a second color tone areain which the first color tone area is provided, the second color tonearea being divided into the first region, the second region, the thirdregion, the fourth region, the fifth region and the sixth region,outlines of the first region through the sixth region being defined byfirst three points of intersection on a perimeter of the second colortone area at which a triangle circumscribed outside the first color tonearea intersects with the perimeter of the second color tone area andsecond three points of intersection on the perimeter of the second colortone area at which dividing lines that pass through the first threepoints of intersection and a center of the second color tone areaintersect with the perimeter of the second color tone area.